Vehicle handling, stability, and bifurcation of equilibrium conditions were studied using a state vector approach. The research provided a framework for an improved method of vehicle handling assessment that included non-linear regions of performance and transient behavior. Vehicle models under pure lateral slip, constant velocity, and constant front steer were developed. Four-wheel, two-axle vehicle models were evolved from simpler models and were extended to include vehicle roll dynamics and lateral load transfer effects. Nonlinearities stem from tire force characteristics that include tire force saturation. Bifurcations were studied by quasi-static variations of vehicle speed and front steer angle. System models were expanded, assessing overall stability, including vehicle behavior outside normal operating ranges. Nonlinear models of understeering, oversteering, and neutral steering vehicles were created and analyzed. Domains of attraction for stable equilibrium were discussed along with physical interpretations of results from the system analysis.
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